1. Field of the Invention
Aqueous processible, alcohol resistant, photosensitive compositions comprising a specially modified polymer of a diene, an olefin monomer and a radical generating system.
2. State of the Art
Reaction of mercapto acids with unsaturated polymers to give carboxyl-containing polymers is known. Such reactions have been carried out in solution, thermally, or with a free-radical initiator. For instance:
British patent specification No. 1,179,252 discloses the use of butadiene polymers containing carboxyl groups in the preparation of thermoplastic elastomer compositions. The polymers were prepared by reaction of a mercaptocarboxylic acid with polybutadiene in solution in the presence of a free-radical initiator.
U.S. Pat. No. 2,589,151 discloses thioglycolic acid adducts of butadiene copolymers, prepared in solution using a free-radical initiator.
Serniuk et al., J. Am. Chem. Soc., 70, pages 1804 to 1808 (1948) discloses addition of mercaptans to ethylenic bonds.
Marvel et al., Ind. Eng. Chem., 45, pages 2090 to 2093 (1953), disclose the modification of polybutadiene by addition of thiols such as mercaptoacetic acid to give polymers with improved oil resistance. Reaction is carried out in solution using a free-radical initiator.
Merrill et al., Research Disclosure, 143, page 24 (1976), disclose the use of mercapto acid derivatives of unsaturated polymers as a component in liquid electrographic developers. The modified polymers are prepared in solution using a free-radical initiator.
Polymeric binders which contain carboxyl groups have been employed previously in photosensitive compositions. For instance:
German Patent Specification No. 2,720,228 discloses photosensitive compositions consisting of (I) a copolymer of (a) a conjugated diene, (b) an .alpha.,.beta.-ethylenically unsaturated carboxylic acid or anhydride, and optionally (c) a monoolefinically-unsaturated compound; (II) a photosensitizer and/or light-sensitive cross-linking agent; and (III) a photopolymerizable unsaturated monomer, useful for flexographic relief printing plates. The carboxyl groups of the copolymer may be neutralized with an alkali metal cation or amine cation.
Canadian Patent No. 614,181 discloses a photopolymerizable composition comprising at least 40 percent by weight of a butadiene homopolymer or copolymer binder including butadiene/acrylonitrile and butadiene/methacrylic acid copolymers, at least 10 percent by weight of an addition-polymerizable ethylenically unsaturated compound, and 0.001 to 10 percent by weight of a polymerization initiator.
U.S. Pat. No. 4,177,074 discloses photosensitive, elastomeric compositions containing (1) a high molecular weight butadiene/acrylonitrile copolymer which preferably contains carboxyl groups, (2) a low molecular weight butadiene polymer, (3) an ethylenically unsaturated monomer, and (4) a free-radical generating system.
U.S. Pat. No. 3,825,430 discloses a light-sensitive composition containing a continuous phase of a light-sensitive organic material and a discontinuous phase of a finely divided, elastomeric organic compound uniformly distributed through the continuous phase, e.g., a carboxyl-containing, high molecular weight butadiene/acrylonitrile copolymer. The discontinuous phase generally represents 5 to 50 percent by weight of the total composition.